I was wondering about this too... My wedding is coming up in a few months and we left the catering really last minute (nightmare I know).
I heard of this new company through a friend called Feast It. On their website you can book street food trucks to cater for your events, and it's much cheaper than normal caterers. I've just started the booking process with them so will let you know how it goes!
Here's their website: feast-it.com/event/wedding